The invention relates generally to lost foam casting and, more particularly, to multi-piece lost foam pattern assemblies for use in the lost foam casting process. Still more particularly, the invention relates to multiple-piece lost foam pattern assemblies and to such pattern assemblies which are particularly adopted for casting a cylinder head for a four stroke internal combustion engine.
Attention is directed to the following United States Patents.
______________________________________ Patent No. Inventor(s) Issue Date ______________________________________ 4,777,997 William D. Corbett October 18, 1988 4,802,447 William D. Corbett February 7, 1989 4,883,110 Morgan, et al. November 28, 1989 4,907,638 Hubbell, et al. March 13, 1990 4,951,733 Kusche, et al. August 28, 1990 ______________________________________
Attention is also directed to Japanese Patent 0282744 granted Dec. 8, 1987.
In the past, multi-piece cylinder head pattern assemblies were constructed, as shown in FIG. 1, from four pieces 11, 12, 13, 14 which were adhesively glued along the three indicated glue lines 21, 22 and 23. It is noted that the glue line 21 extends, in part, at an angle to the other glue lines 22 and 23 and that as a result, the glue line 21 includes two portions 33 and 35 at an angle to one another. Furthermore, a flow piece passage 41 communicating with the exterior was formed, in part, in the pattern piece 12 and, in part, in the pattern piece 13. As a consequence, there was little flexibility in locating the connection of the passage portion 41 with the areas on the exterior casting surface where the passage portion 41 opened to the atmosphere and which were available for connection to fuel/air supply and exhaust manifolds. Specifically, in the construction shown in FIG. 1, any different location of the flow passages relative to the illustrated near optimum arrangement will result in reduced cross-sectional flow area and in an unsmooth passage configuration hindering fluid flow. This problem is particularly serious with respect to multi-cylinder engines.